Biological Oxygen Demand (BOD)

Use & Application Of Oxygen Isotopes In Ground Water Studies

Use & Application Of Oxygen Isotopes In Ground Water Studies


  • Naturally occurring oxygen is composed of three stable isotopes 16O, 17O, and 18O.
  • 16O being the most abundant (99.762% natural abundance)
  • Known oxygen isotopes range in mass number from 12 to 24.
  • 16O is a primary isotope while 17O and 18O are secondary isotopes
Biological Oxygen Demand (BOD)
Biological Oxygen Demand (BOD)

Stable oxygen is used in

  • ground water studies
  • to investigate recharge,
  • ground water interaction
  • surface water interaction
  • Paleo hydrogeologic interactions
  • to estimate ground water ages


The ratio of 18O to 16O in ice and deep sea cores is temperature dependent
Thus, can be used as a proxy measure for reconstructing climate change.
During colder periods,16O is preferentially evaporated , leaving the slightly heavier  and more sluggish 18O behind.

Factors affecting

(i) Temperature change effects
Dansgard (1964) plotted the relationship between temperature (taken as the mean annual air temperature for a  station) and the δ18O value.
From this he derived the graph and equation
Graph  clearly shows the very strong relationship between temperature and δ18O.
This is a response to greater fractionation taking place at low temperatures than at high temperatures


(i) Altitude effects Temperature decreases with altitude. This is again a temperature driven effect.


Thus, oxygen isotopes play a major role in ground water studies which may be helpful for further researches. Its temprature dependency plays key role in its importance.